netdev - [PATCH net 2/2] net: call cgroup_sk_alloc() earlier in sk_clone

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Message-Id: <20171011021233.24158-2-edumazet@google.com>
Date:   Tue, 10 Oct 2017 19:12:33 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Craig Gallek <cgallek@...gle.com>, Tejun Heo <tj@...nel.org>
Subject: [PATCH net 2/2] net: call cgroup_sk_alloc() earlier in sk_clone_lock()

If for some reason, the newly allocated child need to be freed,
we will call cgroup_put() (via sk_free_unlock_clone()) while the
corresponding cgroup_get() was not yet done, and we will free memory
too soon.

Fixes: d979a39d7242 ("cgroup: duplicate cgroup reference when cloning sockets")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Tejun Heo <tj@...nel.org>
---
 net/core/sock.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 70c6ccbdf49f2f8a5a0f7c41c7849ea01459be50..415f441c63b9e2ff8feb010f44ca27303c72aaa1 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1687,6 +1687,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 		atomic_set(&newsk->sk_zckey, 0);
 
 		sock_reset_flag(newsk, SOCK_DONE);
+		cgroup_sk_alloc(&newsk->sk_cgrp_data);
 
 		rcu_read_lock();
 		filter = rcu_dereference(sk->sk_filter);
@@ -1718,8 +1719,6 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 		newsk->sk_incoming_cpu = raw_smp_processor_id();
 		atomic64_set(&newsk->sk_cookie, 0);
 
-		cgroup_sk_alloc(&newsk->sk_cgrp_data);
-
 		/*
 		 * Before updating sk_refcnt, we must commit prior changes to memory
 		 * (Documentation/RCU/rculist_nulls.txt for details)
-- 
2.15.0.rc0.271.g36b669edcc-goog